linux-kernel - Re: [PATCH 4.12 004/106] scsi: sg: fix SG_DXFER_FROM

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Date:   Fri, 11 Aug 2017 09:14:09 +0200
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Chris Clayton <chris2553@...glemail.com>,
        Douglas Gilbert <dgilbert@...erlog.com>,
        Hannes Reinecke <hare@...e.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Subject: Re: [PATCH 4.12 004/106] scsi: sg: fix SG_DXFER_FROM_DEV transfers

On Thu, Aug 10, 2017 at 08:11:34AM -0700, Greg KH wrote:
> else between it and the newer one?  Drop this and you provide a
> backport?  Something else?
> 
> Totally confusing...

Sorry for confusing you, here's the backport for your 4.12 stable branch,

Thanks,
	Johannes

>From 469957522c4b356a313cb369e3e14fdac104370f Mon Sep 17 00:00:00 2001
From: Johannes Thumshirn <jthumshirn@...e.de>
Date: Thu, 27 Jul 2017 09:11:26 +0200
Subject: [PATCH] scsi: sg: only check for dxfer_len greater than 256M

commit f930c7043663188429cd9b254e9d761edfc101ce upstream

Don't make any assumptions on the sg_io_hdr_t::dxfer_direction or the
sg_io_hdr_t::dxferp in order to determine if it is a valid request. The
only way we can check for bad requests is by checking if the length
exceeds 256M.

Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
Fixes: 28676d869bbb (scsi: sg: check for valid direction before starting the
request)
Reported-by: Jason L Tibbitts III <tibbs@...h.uh.edu>
Tested-by: Jason L Tibbitts III <tibbs@...h.uh.edu>
Suggested-by: Doug Gilbert <dgilbert@...erlog.com>
Cc: Doug Gilbert <dgilbert@...erlog.com>
Cc: <stable@...r.kernel.org>
Reviewed-by: Hannes Reinecke <hare@...e.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
---
 drivers/scsi/sg.c | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 82c33a6edbea..aa6f1debeaa7 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -751,29 +751,6 @@ sg_new_write(Sg_fd *sfp, struct file *file, const char __user *buf,
 	return count;
 }
 
-static bool sg_is_valid_dxfer(sg_io_hdr_t *hp)
-{
-	switch (hp->dxfer_direction) {
-	case SG_DXFER_NONE:
-		if (hp->dxferp || hp->dxfer_len > 0)
-			return false;
-		return true;
-	case SG_DXFER_TO_DEV:
-	case SG_DXFER_FROM_DEV:
-	case SG_DXFER_TO_FROM_DEV:
-		if (!hp->dxferp || hp->dxfer_len == 0)
-			return false;
-		return true;
-	case SG_DXFER_UNKNOWN:
-		if ((!hp->dxferp && hp->dxfer_len) ||
-		    (hp->dxferp && hp->dxfer_len == 0))
-			return false;
-		return true;
-	default:
-		return false;
-	}
-}
-
 static int
 sg_common_write(Sg_fd * sfp, Sg_request * srp,
 		unsigned char *cmnd, int timeout, int blocking)
@@ -794,7 +771,7 @@ sg_common_write(Sg_fd * sfp, Sg_request * srp,
 			"sg_common_write:  scsi opcode=0x%02x, cmd_size=%d\n",
 			(int) cmnd[0], (int) hp->cmd_len));
 
-	if (!sg_is_valid_dxfer(hp))
+	if (hp->dxfer_len >= SZ_256M)
 		return -EINVAL;
 
 	k = sg_start_req(srp, cmnd);
-- 
2.12.3


-- 
Johannes Thumshirn                                          Storage
jthumshirn@...e.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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